If you have a lift in the middle of your roof with nothing around it, it could be a plywood pop, a sure sign of your shingles lifting.
When you install a roof, you have to leave a gap in the deck. If you look down at the sidewalk, you see little lines cut into the concrete. Those are called expansion joints. Everything, including your roof, expands and contracts. It moves. So have to leave space to allow that.
Underneath your shingles, under the tarpaper, you have plywood. If your roofer didn’t leave a gap, or it wasn’t big enough, over time the plywood gets closer and closer. Finally, it has nowhere to go and the two pieces of plywood are pushing against one another. One eventually gives and literally pops the plywood up, causing a big buckle on the roof.
"Plywood pop" due to expansion
If you have a really steep roof, you probably won’t get a leak. But on lower slope roofs, depending on where the pop is, water can get stuck like a trough. Water won’t be able to get off the roof and you’ll get a leak.
The only way to fix it is to take all the shingles and paper off, go down to the plywood, re-gap the piece, and put it back together. If you’re having multiple plywood pops, you might need to re-roof.
Roof Life of Oregon always does plywood prep before a re-roof. We make sure all the plywood is re-gapped. That keeps you from having a plywood pop and a leak later down the road. Most companies just tear the old roof off, remove the nails or staples, and go to town. Not us.
Call Roof Life of Oregon if you have a plywood pop, or if you want to hire an experienced team to re-roof your home.